Britain’s electricity generators have been forced to warm up coal-fired power stations for the second time this winter. 

The ESO (Electricity System Operator) branch of the National Grid said the three generators - two at Drax's site in North Yorkshire and one at West Burton in Lincolnshire - will not necessarily be needed, but that the instructions were given in preparation for tighter supply margins during the cold snap. 

The plants on standby were originally set for retirement, but their lives were extended through this winter in a bid to boost supplies amid energy security fears.

“Our forecasts show electricity supply margins are expected to be tighter than normal on Monday evening,” the ESO said. “We have instructed coal-fired power units to be available to increase electricity supplies should it be needed tomorrow evening.

"The ESO as a prudent system operator has these tools for additional contingency to operate the network as normal and the...